ISOKIKETIC SAMPLING OF AEHOSOLS FROM TABGEjrrtAU Plow 5TREAHS A DISSERTATION PRESENTED TO 1T!E GRADUATE COONCIl 01 IWE UNIVERSirr OF FLORIDA IS PARTIAL FDLFllUlEirr OF THE REOUIREIEOTS FOR THE UNIVERSITt OF FLORIDA ACEfOKLEOSEtlE-NTS R803692-01) froa tha Environaental Prntectign Agency (EPA), i ■ortitored by EJA's Project Officer Kenneth T. Knapp. Inportant part that they played in ay edocaclon. I an eapocially appreciative of Dr. Umdgren for his guidance, oocouragCBant and preparing this oanuscript- Finaily, 1 wish to thank ay parents through the difficult tin COm-ENTS £5S« 10 ISOKINETIC SAMPLING Tl IE PERTINENT LITERATUEE, . . AnlKakfjiatic SanpUnj Noisle Mlsaltgimenc EXPERIMENTAL APPARATUS AK UaloclCT DeteTnlnation. . . KUW RATE DCTEaWNED AT VARIOUS MEASUREMEUT LOCATIONS.. CONCGKTRATION AT A POI.NT POR BIFFEREHT SAFIPUNC ANCLES. MISSION TEST RESULTS SIZES AND DESCRIPTIONS OF EXPERIHEJTAL AEROSOLS TABLE OF OSTAIXABIE VELOCITIES IN 10 nn BOCT TYPICAL MLOCITY TRAVERSE IN THE E.IPBRUEOTAL SAMPLI.NG RESULTS OF SAUPUNC WITH TWO PARALLEL NC PERCENT OP PARTICULATE JIATTER COLI.EaED FOR NOI'LES PARALLEL WITH THE FLOW STREA PERCENT OF PARTICUUTE HATTER COLLECTED FOR N02EUS AT AN ANCM OF 60 DEGREES WI ASPIRATION COEPFICIENT AS A FUNCTION OF 30 DECREE MISRLIGNMBJT ASPIRATION COEFFICIEKT AS A FUNCTION OF STORES .NUMBER FOR 60 DECREE MISALIGNMENT ASPIRATION COEFFICIEMT AS A FUNCTION OF STORES NUMBER FOR 80 DECREE MISALIGNMENT COMPARISON OF SAH’LING EPFICIENCT RESULTS WITH THOSE OF ASPIUTIOS COEFFICIENT AS A FUNCTION OF STORES NL81BER FOR m COEFFICIEHTS CALCULATCO K ASPIRATION COEFFICIEKTS CAICULATEO IN THE SIMUUTIOK WDEt FOR THE HIGH FLOH CONDITION RCSUITS OF THD CTCLDNE OWIET SIMILATIOS MODEL FOR THREE CONDITIONS SUIHARY OP E5DATION5 PBEOICTING PARTICLE SAMPLING BIAS... projected area of saaplor inlet coQccncrction ratio of aoroaol generating aolution particle diarecer distance upstrean froni noazle stack velocity velocity viscosity angle flf BiisaUgnosnt of nottln with rospecc to l A therefore el developed to edjust the Stahes nunber to eccount for i Using an aquation enpirleally developed fron the* using the equations of Belyeev and tevin describing aj bias with zero eiselignaent, a omchematical aodel was which predicts the sampHni error when both noszle alt iineCic sanpllnj velocities occur siaoltaneously. It was found that the saoplins bias approached a aariBuri error tl>ScosB| where R is the ratio c the free stream velocity to the sanpling velocity. During the testiug, i IS 60% of the particulate oatter entering the The causes and characteristics af tangential flaw streans ore described as they relate to probleos in aerosol sampling. The lialtations of the S-type pitot tube when used in a svirlinE flow are discussed. A three dinensionol or five-hole pitot tube was used to oap cross sectional and asial flow patterns In a stack followlni the outlet of a cyclone. Anglos as great as 7D degrees reletlve to the axis ef Che stack and n reverse flow core area were found in Using infonmcion found In this study, a sloulation oodei was developed to dccemiiie the errors involved when Baking a Method 5 analysis in a tan- gential flow streaa. For an aerosol with a 3.0 ua 1»ID [nass oean diaaeter) and goradlrie standard deviation ( 5 ^ of 2.13, the predicted eeracentratlon end a a of 3.3, a 20i error wns predicted. Flow races detenclnad by the S-c/pe pitot tube ware from 20 to 30% jrontor than the actual flow rate. ImplicacinDs of these results are described and racomMndntiona for aodifica- taniceotial flow stress ore Introduction This stud/ deals wi sanple of particulate matter from a gns stream chat does not flow parallel to the axis of the stack as in the mass of s-lrllns or tansentlal floe. This type of floe is eoimeonly found in stacks and could bn the source of subscantisl snmplini error. The causes and •s particular flow paccem are described and rate determinations are thoroushly anal/tod and discussed. The analysis of sajnpling errors is approached from two directions in this study. One approach involves an investigation of aerosol sampling bias due to anisokinetic sampling velocities and misalignment of the nozalo with respect to the flow atreatn as a function of particlo nod flow characteriitles- The second part of the study involves en accurote mapping of the flow patterns In a tangential flow aystem. The inforeatlon obtained in the two parts of the study will be combined Method 5 (i , 2] analysis in a tangential flow stream. tsoklnatlc SMpUnt To obrain a represontatiyo ftaople of poTtlCDlote Batter from a ooviri fluid. It is necessary to saaplc isokinetlcally. Tsakinetic seopliftg can be defined by too conditioner (3) 1) The suction or nosalo velocity, V^, oust bo equal to the free streasi velocity, V ; and 2) the noszle Bust be aligned parallel to the flow direction. onterlnj the nocile. {see Figure 1). Thus, there Kill bo no divergence of streamlines either away frcoe or into the nettle, and When divergence of streoBlinss is produced by superlsohinetic sampling, subisoklnotlc sanpling or noetic misBlignaient, there is a possibility of particle size fractionation due to the inertial properties of particles. In the cose of superisokinetic sampling [see Figure 2), the sompUng velocity, V,, is greater than the free sampied- A^', will be greater than the. frontal area of the sampling will enter Into the nettle. Particles ootsldo this area but within ic larger perticles will be ur bo sanpllng nettle. Since no velocity is less tine the free stress velocity Cso» Figure J) . In this plod area of the flov, The volusc of air lying aithin the projected area, Aj’, but outside aill not be saaipled and the streasllnos will diverge croued the nozzle. Hoaever, some of the particles in this area. of the particles within A , caused by snpsrisoblnetic saspling. When Therefore, whenever the noztle is misaligned, the if anisokinetic sampling [superisohinetic, concentration error will depend upon the sice of the particles. More specifically it will depend upon oarticle inertia, sdiich iaplies that the velocity and density of the portlcte arc also inrportimt. Portlcle inert!* affetts the ability of the particle to negotiate turns with its streenline which deCemlnes the seiount of error. Therefore, in ail cases greater saiapUni errors will occur for larger particles an4 Besides dotervining the direction of the sampling bias, it is also possible to predict theoretically the ninimuB and noiioan error for a given condition. This con be done by considering whnt hsppens when the Inertia of the partlclei ia very small (i.e.. the particles can negotiate any turn that tha stmaalines mabe] and what happens when the inertia of panicles is very Itrge (I.e., the panicles are unable to negotiate any turn with the streaiallnes) . In the former case of very low inertia, it can easily be seen that since the particles ore very mobile they do nut lesve their streamlines and therefore there will be no sampling bias. In this situation the concentration of sampling depends oi ye accurately obtained regardless of sampling ■ 0 is obtained for amall inertia panlcles- :hat can theoretically occur in anisobinetic In the case of unequal velocities for very high inertia particles *Aich are unable to negotiate any change of diroclion, only those particles directly in front of the projected area of the noillo, Aj. will enter the nostle regardless of the sampling velocity. Therefore, PEBTISENT LITiMTURE le litei-iturg on Aplaokinelic Sfplin | Sa»pllm 8ia» Du» to UnnitchtJ Vi Numerous eiticles hsve been urltten destriblnj tHe sources end rapilcudc of errors when isokinetic conditions are not sslncained. In one of the ceriler uorks, Lnpplo end Shepherd (4) studied the trajectories of particles In s flov stroajn and presented a fonmila for estiMtIoj the order of the magnitude of errors resulting alien there is a difference boteeen the average sampling veiocity and the local free stronn velocity, hatsem CS) examined errors in the anlso- diameter (iKO) and found the relationships shown In Pigure 5. Super- isokinetic sampling (aampllng with nottlo velocity greater than the free stream velocity] leads te a concentration less than the aetuai concentration, while subisoklnetlc sampling hos the opposite effect, tfatson found that the magnitude of the error was not only s function of particle site as seen In Pigure 5, but also of the voioeity and the notile diameter. He propoeed that the sampling efficiency was a function of the dimensionless particle inertial parameter K (Stokes numher) defined as ; « Cunninshnm eorroctlon for slippvge r - PpOp'/Un 1 - viscosity of gas correct tvichin IQi, the velocity ratio R «ust lie becveen 0.R6 end 1-13 particles. datcctablo concentration changes even while saepling at a 4003 variation relatively onlaportant for fine particles. Heneon and Haines (7} site ranges (5-2S, 80-100, and dOO-500 pm) and in a range of norslo to staefc velocities of 0-2 to 2-0- They found that where the velocity proxinatciy 803, and that deficient noaile velocities resulted In greater for the coarse particles, the velocity into the noaale had no important besrins on the quantity of dust collected. They suggested produce of the nostle area and the stack gas velocity approaching the nettle as tho gas senplo volimo, regardless of Che velocity of the Is possible to obtain small deviations even where departure from sampling anisoklnoticany For large particles, Lundgren and Calvert (9] found the sampling bias or aspiration coefficient A, to be a function of the inertial impaecicm parameter K end the velocity ratio R. They developed e chart which can be used to predict inlet anisokinetic sampling bias depending on both K end R. Redtloch's (lOJ oquacions defined the dependence of the efficiency upon particle inertia and the velocity retio. In a allghtly different teminoiogy A = C./C^ " I • (R-1) 8(K1 (S) where B[K} Is a function of inertia given by 8tH • [ 1 -exp {-L/t)]/(L/« C6) g Is the stopping distance or the discanco a particle with initial is defined by ( 11 ) L is the dlstence upstream from the nozsle where the flow by Che downstreen nozzle. It is e function of the nozzle is ^Iven by the equation; is undisturbed diameter and hem to verify Badzioch's claim that L, the undisturbed distsnee anisokinetlc sampling F previous studies on or BCK.R) :t slsnificant changes li Figure 6 ahovs a plot of eqoations (5] , BOFonB R a 1, Che aeplration coefficient cends co as9ympcaciceU>r ap- proach its cheorecical lieit of R. Reyoml a Scokoe number of about il consideretlona. Bodtioch (IB} and Belyaev and Lovln [12) IB screajDiines a art to diverge at approxioetely 6 directions in an anount of tine the linlclng sice particle ttialyzins concentration errors olotsined while sateplinf suboiicron particles, O.S ub XhS> and 1.26 jeotiietric standard deviation, traveling sanpllng velocity wos 206 oP tho free screen velocity (ReSl- field was eisintaincd or assuned c probe niaalignnent do not provide enough puantilntive reported by Ifatson (61. on Che effect of eisaligntwnt efficiency of 4, 12 end 32 Oat particles (see figure 7). In a : lecced the highest concentration. Although Figure 7. Error due to aiselignioent of probe to flow Hayhood and Langstrotb, in Katson {E)J. theoretical predicciotis fi.e., aeasured conceatraTion 1; inportanc paroaeters, free atrean velocity at lot included in the analysis. »lod speeds of 100, 200, 400 and 700 ca/sec vith the notslo aliened over a rnnje of ongles froo 60 to 120 dojrees- He then used a trijono- a • 1 • e[«[(VjSlne V^CO!B)/IV|C05« • V^sinO) - 1] (11) serves to invert the velocity ratio betveen 0 and I not realiscically represent the physical properties In tact, equation ClI) hecooes unity at 45 defroos the velocity ratio or particle site is. This cannot 1 decroase inversely proportional to the angle and A more representative function can be derived in the following velocity V^, let ho the cross sectional area of the nettle of dianetcr 0 in ecoistiem (U) to r< iB the Jiniting situation for a pnrcieie to proportional to the avcroge OiaButer of the frontal area of the not) Puchs [19) suggests that for srsoll angles the sampling efficiency wl Laktionov [20} sampled a pel used a photoelectric instellatlon cion coefficients for different s ever a range of Seohes nunbers fri three subisoklnctic conditions. He :ed particles. Pron data obtained 1 0.003 to 0.2 he developed the fol- A few w»lni=al studies in this .rea hate also been published. Dasio!’ ( 14 ) theoretical calculations of pottleU trajectories in a nonrlscous flow into a point sinh deterained the senpling accuracr to be a function of the oostla inlet orientation and dia.eter, the sasiplinB flow rote and the dust particle inertia. Vitols (Jl) also •ado theoretical oitlnates of errors due to onlsoklnctU sanpllni. Ho used a procedure conbininB an analog and a digital coaputer end considered inertia as the predoininent ■echnnism in the collection of the particulate itatter. Howocer. the results obtained by Vitols are only for high values of Stokes numbers and am of little value for »^_Sierory of the lltarcture en Tinientlal Flow ;c aampling velocity is known ti particle saapling bi (e.g., centrifugal, electrical, gravltetlonal or therMlj; and probe mlsollgiuaenc due to tangeatlal or circulation flow. These factors ai al«n always present in an Induscrial stack gas and cannot be assuiu to be negligible. Not only do these factors cause sinpling error directly but in addition, they cause particulate ct and aerosol size distrlhution varintlons to exist a Tangential flow is tho non-randotn flow in a direction other than parallol to the duct center llua direction. In an air pollution control device, Hhcmever centrifugal force is used ns particle collecting aeehanism. ungentiel flow vili oecur. Css flortng fron the outlet of a cjntlono is a classic erasipU of tongeaciol flov and a well recognised probleo area for accurate particulate sampling. Tangential flow can also b. caused ty flow ch.nges induced by ducting tangentially, a T Csee Figure 9), Ever within an order of oagnitude of tho stack flow flow pnttom will occur Csec Figure 10). The swirling flow in the stack combines tl vortea laoticFn with asisl motion along the stack avis The gas stream moves in spiral ar helical pacha up tha stack. Since this reproscnts a developing flow field, the swirl level decays and the velocity pro- flies and static pressure distributions change with niial position nous ere composed of aiiol, radisl and tangential escabl ished tangential or or circumferential velocity components Cs«e Figure JI). vortor flows ore generally amisyeanccric but during formation of t: spiraling flow tho s.vmmetry is often dietorted. The relnllve ord. magnitude of the velocity components veries across the flow fiold the poasihllity of each one of the cottponents becoming dominanl ai Fljur. The two distinctly difforont types of flow that are possible in When the swirling cospcmedt of flow is first created in the cycloee exit, the tangential profile of the Induced flow approaches that of a by dividing it is loss of angular ■omentum is due to viscous action angular noniontuia and tengentiai 1 and tangential point volocity ■ tangential velocity profiles and la distributions are plotted in Figures 12 and 13 fron lien at 9. 24 and 44 diameters dawnsciesD of the origin 'low. The tangential velocity (VO is made diaensionless by the mean spatial axial velocity CU,) at a pipe cross developacnt i» due prinsrily to yieeoslt/ e1 vary dependent on the in suirle may produce reversed axial velocities in the central region (21), It should be noted that although tangential velocities and angular after S4 diameter the tangential velocity is still quite significant vhen eoapared to the axial velocity. Therefore, satisfying the GPA the tangential component of velocity was as high as SO degrees at some m gradients and invalid flow described In the previous chapter. Concentration sradients occur because the recatitmsL flOM in Che stoc): acts aoaeuhac as a cycione. The centrifugal force causes the larger particles to move touotd the to deteteine the teagnlcude of th cyclonic floe. Results of floe ot of a small industrial cyclone determined at the different errors can result in cases of tangential flm. eleiost 741, Hhen sanpling domstreosi of the however, the error was reduced to 15^. degrees UKATIOKS '8 DETCBHISED AT VABIOU5 Saapllnjt at the anfle of Baainun velocity head i to The reaults cannot be coapared directly tc parallel aanpling approach because the feed rates were not the scuiie duo to equlpnent failure end repUcetnont- Sasipling in the straighconed pacted on the etraightening vanes and settled io the hcrritootal section of the duct, thus ressoving theta froia the floe streaei. Particle siae distribution tests showed no significant effect of portieles being too small to be affected by the centrifugal force field sot up by the rotating flow. EMSSION TEST RSSUI.TS Aclusl Ejoission Hate tgr/js en Scnlfhtgnad sijice It has larga dioaeter pressure part that uill not plu| (see rts It has on additional SQBevhat insensitive to i and 16 shoe the veioeity 5-type pitot tube is vorj ihe for a given velocity. Houever, although I give an accurate velocity aeasurement. It is irrors for yaw and pitch angles. Although the luse of this Insensitivity to direction of flow S-type pitot tube cannot bo used in a tanEontlal The Bagnitude of the radial and tangential conponents relotive to the axial component will doteminn the degree of error Induced by the tangential the flow rate through the stack, but both affect the velocity neasureitcnt inado by the S-type pitot tube because it lacks directional sensitivity. If the maxljfruiB velocity head were used to calculate the stack velocity, Therefore, tube in cingontinl flo» 1- Methods Jtvellible fc PToi Pielj ~ M neither the rsdlel velocity, V . th irial velocity, V^, nor the enjle « ct a tenjeotial flo» field hive been hised upon introduction of probes Into the flou. Becnuso of the sensitivity of vortor flo.s te the Introduction Tvo comnion types of pressure probes capible of aeosuring velocity >c dinenstoncl directional a henisphericnl or conical probe tip one on the axis and at the pole of the tip, the other four spsced equidistant from the first and from each other at on angle of 30 to SC degrees frets the pole. The operation of the probe is based upon the surface pressure distribution around the probe tip. If the ptobe U then a prassure differential vill be set up aerreas these holes: the inasnltude of uhleh «ill depend upon the geometry of the probe tip, relative position of the boles and the magnitude differencials becveen holes as a fuoccion of yaw and pitch anples. Figure Id shows the sensitivity of a ty'pical S-hole pitot tube to ynw angle. Because of its sensitivity to yaw angle, it is possible to rotate the probe until the yaw pressures are oijnal, ueasuro the angle of probe rotation tyaw anglel and then determine the pitch angle from the re- maining pressure differentials. The probe cin be used without rotation by osing the cosplete set of oalibrotion curves but the ceaplexity of ■eesureaent end calculetion is increased and accuracy is reduced. Vel- ocity coiponents can then be cslculated froo the measured total pressure, stetic pressure and yaw and pitch angle aeasurements. unable to measure pitch angle. The probe is character! tod by a central total pressure opening ol the tip of the probe with two static pressure degrees. From Figure IS it con be soon that the probe is quite sensitiv to yaw angle and can therefore be used to determine the yaw angle by rotating the probe until the pressure readings at the static taps are S. EPA Criterii fet Saapliog Cyclonic Flew The revisions to reference methods 1-g (2) describe a tost for deteminneion of whether cyclonic flow exists in e stock. The S-type Figure IB. rccHctmer pitot luhp ronttltlvlcy to >-ow angle. C2B) m relative to the le ^essure reading je ij used to detenine the angle of the f] ■ho stack by turrdni the pitot tube until i id of Method 5 should he used to ssnple the 'o procedures include iestallotion of straightening vanes, celcoiotinj the total voliaietric flou rate stolciioeiotrloally, or moving to another masauresent site at vhich the Straightening vanes have shonn the capability of reducing suirllng the physical Unltation of placing then in an eslsting siact. Another ia the cost In terns of energy due to the leas of velocity pressure vhen ollnilnstini the tongcetlel and ridlol conrwnonts of velocity. Since the vorteg flows are so sensitive to downstroon disturbances, It is quite possible Chet straightening vonee might have e drastic effect on the performance of tho upstream cyclonic control device which is genemting the tangential flow. Because of these reasons the use of straightening vsjies is unacceptahle In many situations. Calculotlng the volumetric flow rate stoichlomotrioally might CBlculatc tho necessary isokinetic samnling velocities and directions. Also, studios renortod hero have shown that the decoy of the tangontiol eoopooent of velocity in circular atocks is rather slow end therefore it would be unlikely that another mensurenent site «old solve the problem. as obsorvlng tl 8 BtscV is correct. Other approaches such n of the plume afeer leevlng the stack could I [28) f, twin-spiralioa vorticlos often seen leaving stacks secondary flow effects geoerated by the bending of A. Expcrtfttflntat Design Pigure 20- An aerosol stream ganeriled Prom a spinning disc genamtor was fed into a nlxinf chojiiber xhera it wos coabinad »ith dilution alt. The air stream then flowed through a 10 em dlamoter PVC pipe containing straighconing vanes. This was followed by a straight section of clear as a control sample originated In a box follOHing the straight seetlen. A test noaala was Inserted into the duct at an angle from outside the box, A thin-plate orifice, uaod to monitor flow rate, followed the through the systaa. The flow t dieieetor of an orifice plate. An air by-pass between the blower and the orifice plate wea need as a fine adjnst for the flow. The aompUng systow (sou Figure llj consisted of stainless steel, :ted to d 7 am stainless steel Gelman filter Each filter asaenbly was connected in scries to a dry gas ind 0 rotameter, end driven by an airtight pump with a by-pass .0 control flow. by changing tl TO PLHPS AND GAS METERS MANOMETER MOToaispSTso o»ro5»u froo 1-0 NMD to 11. 1 » NMD (seo Tatu IVJ . Droplota «org generated fro* a sLiture of 5D% uranine (a fliioresoent ethanol (9S» pure) and up to lOt distilled/deioniied lljO. Uranine »os uaed ao that the particlea could be dotocred by fluoreaetrie aethods. Methylene blue xaa added to aid in the optical stiiej of the particlea. The Birture of water end ethanol allowed for a unifora avaporotion of the dropleca. The droplata, containing dissolved aoluto, evaporated to yield particlea whose dianeters could be ealculated from the equation D = particle diaaeter, uti ■ ratio of solute volune to solvent volutae plus solute voluae, diaensionless Dq ■ original droplet diametar, |aa With Iho diac'B rotationel velocity, air flows and liquid feed rate holt constant the site of the droplets produced were only dependant upon tho a dynamic force balance between the centrifegal force end the surface IB DESCRIPTIONS OF EXPEBIMENTAl. A1 Ethsnol Diameter, uj Spinnins Disc Spinning iliac Spiening Disc Spinning Diic Spinning Dlac Spinning Disc Spinning Disc Spinning Disc Spinning Disc ro respectively 72.5 anrt 22.3 dynes/ctn f3 C. Velocity Deterainition The velocity el eech sonpllnj point ns lOMSured using a standard trolling the pressure drop across a thin-walled orifice placed in the system [35-37]. Five orifice places with orifices ranging in disneter A typical velocity profile across the 9.5 cat clear plastic duct is presentod in Table VI and plotted in Figure 22. The profile la Reynolds m yr this particular case was 1.1 x 10^. The velocities of isokinetic sampling rats and StoVss nuinbar. The difference between plate calibration is probably due to the inability of Che pitot tube to existed across the diameter of a cylindrical duct, and that the magnitude of Che concentration gradient varied with particle size. le noztles were made approximately IS cm 10 dlsturfaanoe caused by tho filter thereforr. ne«s, the releUve ectge thickness F, Anslysls ^ecedure Uranine particles were collected on Gelnurn t/pe A floss fiber filters. The filters vere then placed in s 250 ml boaher. One hundred sllllliters of distilled wsur vere then pipetted into the front half of analysed by a fluoroneter (39] . le particles were 5.0 ub type SH Millipore membrenc filter.s. In ardei therefore, each filter wes dyed with inh and a grid ue$ draws to aid in the counting. Sefore being placed in the filter holdere, the filters with black gride. The Isopropyl reiBovo background particulate aai the alcohol was poured into the 1 through the notrlea. The solutii filters. The filters were allowed to dry and filter holder wan analyiod ce the background wan low enough. Saepline Procedure Ig the by-past as a fine ad}uat. 'as ncnsured using a standard pitot tube, sit solution was selected for a given particle uslag n light microscope. saopligg race clasoet to 1 Isokinetic snnpllng rates flow rates were adjusted accordingly- angle- SanpUng tines varied froo IQ to 20 nlnutes. The syeten used tc tr, follawed by e 6.1 meter length ef 2G cm PVC Pitch angle is then detenined CyclDM boajuro ae the flow perpendicular to the axis of the stack and tangent to the stack walls. The pitch angle is o neasuTe of the flow perpendic ular to the axis of the stack and perpendicular to the stack walls. Th where = eooponent of velocity flowing porallel to the axis of the [cosCpitch) X cosCyaw)) CHAPTEH IV RESULTS AKD ANALYSIS A. Aerpsol Sampling EKperiwants EApcriaencs wnra sat up and run with StoVos number ss the Independent variable. Duct velocity, notsle diameter and particle diameter were varied Stokes number used in the analysis of data was calculated from density of ragweed pollen ° 1.1 g/cn^ tlB} DO ac both acmpUng locations, sianilcaneoua saoples This can be aapected because a staall error in jrrobe nlsalUnnenc would have a greater effect at the higher Stokes nuaber. In the enalrsis of the tests using ragweed polien, the filter particle, analysis of the probe wash Is a necessity. An average of parallel to the flow stream and sanpling isokinetioally. Therefore, the loss of particles was due to turbuleat deposition and possibly bounce off the filter, and probably not inertial Inpoction, For tests impnetion of particles PASTICUUTE MATTBR COUECTEB IN THE PTOJE WASH NOZ:iBS PAEALLEL WITH THE FU!W STBEAM degrees (see The probe «»sh for eljht tests using 4.7 u> uranlnc particles was also ajialyted separately for comparison with the results of the ragweed pollen tests- While parallel sampling, from IS to 3Sb of the holder, while this was somewhat less than the amount of rogweed pol- variatlon of the percent collected in the nozile during identicnl tests, the probe wash cannot be accounted for by n correction factor. During further testing, it wes qualitatively observed that the percent in the probe wash increased with particle site and decreased with increasing nottle dlaaetor. t. The Effect cf Angle aitsel Itoment on Sempllne Efficiency The aspiration coefficient wes determined by comparing the amount of particulate matter captured while sampling isohinetioany with a control noasle pieced parellel and a tost noaslo set at an angle to tl For all three angles the aspiration coefficient approached I for smaU minimum cf cosfl for largo values of Stokes number. The most DEGREES KITH THE FtOHCTR^ IS rspresent the sejnpHng efficiency as a randoiBl/. This was done to check the lojitljiTacy of uslo| Stokes nurobor dianecer is Laportant because it deteimines Che amount of time available areo and cherofOTO the projected notzle diameter ore reduced proportiooel d r Iih coefficients for 30, 60 and 90 degrees should approach tbelr theoretical aniscklnecic sampling velocities (see Figure 6). To develop the adjustment factor for Stokes number. It was neeos- O.S. Therefore the value of k of Interest is where there is (,9Sj(0.51 - not possible to detect esaetly when the curve reached 9Sk of its niniinum value. Therefore no value for 30 degrees was used In this anslysl.s. The equation for the adjusted Stokes number determined from Figure be imjltiplied by 1.93, While ectetnpting to determine the constants a and b, it wae found that the fore of the eouation had to be altered swnewHat to allow fl' to approach 1 at a faster rate for ualuos of h’ greater than 4.0. The fol- lowing is the flnoZ form of the equation selected. sempling efficiency due to noitlc misalignment as IS nuabor. An oxamplc of this dotroBS. Iti order to ssmplB isoklnccicslly such thot thcro is no dlvergencB of streamlines into the noxslo, the sample velocity the condition of H e lynose defines Che condition for obtaining a reprosnntative saaple xhen the nosiie is misalignod «ith the flov Since Che snnpilng acthodologies used to determine fiCS<h} fi’(K,9J were substantially different (photoiraphic ol sampled isokinotically and the tost notile sampled anisoklnctlcally. Tests uere porfomied at tvo Stokes numbers (k = 0.1S4 and k • 0.70) and at tuo velocity ratios (B = 2.3 and R = 0,51). The aspiration coefficients obtained by comparing the tvo measured concentrations are presented in Figure 33 and Table XIII. The data obtained lie vithln data [Equations (5), (9) and (10)|. Since tho two methods give conparable results, experimoncs wore flow streoB end the sampling velocity was set to be isokinetic. The velocity. in Tobies XIV and XV, Thosodaca ore plotted and conpared with the aodel's prediction in Plguto 34. The aspiration coefficient does indeed appear to bo unity uhen B = l/cos8 as in the ease of B = 2 and « • eo degrees. limit of RCO50 CO. 25) at approximately a value of Stokes number of 2 to a degrees, R b i approaches its theoretical Unit. This further confirms the necessity of using an adjusted Stohes number vhen the probe is mis- aligned with the flow stream. To ftkrther test the nodal, experiments were run at 45 degrees in Tables XVI and X\1I arc plotted in Figures 55 and 56 also show good When tests were run at 9 s 90 degrees, R = 2,1 and K = 0.195 Csee Table XVIII) , an average aspiration coefficient of only l.Si was obtained The value predicted for equation 131) for these conditions is 49t. it with ths prediction nodel, they do compare favorably Kith the ettpericol equation of Lahtionov {20] [equation (16]]. For the conditiona of r » feet that two completely different sampling schemas were used, and . Tansantial FI . H'a’i”! occording to EPA Method 1 (1) [see Table SIX). Messuremonts vere made each point in the traverse, the pitot tube uns rotated until the pres- froB ail five pressure taps were recorded for later cslculation of total During the Initial velocity tt the flam could not be IS charactoriaed by LOCATION OF SAMPLING Tobies XX-XXIV shOM Che colculaced results of the eeloclty mcesure- nients Bt the five axiol positions. The low flow was the flow Boasurecl when e Tcstrictlon was placed at the Induced Bpproxioacely a 40\ decrease represented o voluaietric flow rate of ^ 5k sir 3S£ - point to thff opening, one ol \e pitch pressure poin if the dste. The velocity- in. flov rates and all five aaial distances showed approsimately the sane characteristics. The pitch angle increased freo the core area to the core area to die walls. At the inlet and up to eight dianetors dtnm- strenm, aoglos as high os 70 degrees were found near the core area of Che flow field. The total velocity, aaial velocity, and the tangential velocity all showed the sane cross sectional flow pattom- The velocities were ninlnun ot the core, increased with radius and then slightly dccrcasod near the wall. These patterns arc similar to those found in the swirling flow generated with fixed vanes [23) . In otdsr to observa the changes in the flow as a function of axial distance fro. the Inlot, Che cross seotloa.I averages of the angle *, core ares, sad tangential velocity were calculated and presented in Table XXV end plotted In figures 35 and 39. All three parameters show e very gradual decay of the indicators of tangential flow as was expected from s [23). IS confimod by repeated AVERAGE AS A FUKCriON OP CROSS 5ECTI0VAL VAIUES OrSTARCE OOkHSTREAH ANH FLOB RATE Avoraje Vnlutj for Hi|h Floi Diajn«tn'5 4 Ektwnstraajn fEegrccsl Location of* Tongentisl Velocity Cote Area Core Atea fowl [co/sec] fca’] Average Values For Low Floe velocity nt 2 diajnotors fron .n Hvernge tangential !r velocity seen fren the other profiles tt bisber velocity average. Plotted in Figure 40 is the location of the core area with avisyannecric and the location of the core area changes It axial distance. Only one drawing is used to ropresenc the situation ft both high and low flow rate because the location for both conditions wi aiAITER V SIMUUTira OF AN ERA METHOD S EMISSION TEST IN A TANGENTIAL FLOIt STBEAfl A MNlel h05 bAsn dbvolopsd snd test«d wlilch doscribes particle collection efficiency as a function of particle characteristics, angle of nisalignaenc, and yoloclcy ratio. Together Hith Che neasuresent of velocity components in a svirling flow it is possible to analyte the analysis of the effluent stream folloviitg a cyclone. For this slnolation enalysis, the volumetric flau rate end iso- hinecic sampling velocities aro cslculnted from velocity aeosuremencs obtained at the eight diameter saagiling location using a S-type pitot tube (soo Tables XICVI and XNVII) , The angle d, velocity ratio, and particle velocity aro deiettiined from velocity oioasuroiaonts made at tho same location using the five-hols pitot tube (soo Toblo Mill- The particle characteristics are obtained from particle size discribotion tests node by Mason (22) on basically the same system. From a particle distribution »ith a 3.0 ua reiD and geometric standard devistion of 2.13 (see Figure Cl), ten particle diameters were selected which represent the midpoints of IDi of the mass of tho aerosol (see Table mill). Tho density of the particles was assumed to be 2.7 g/cm^. The nozzle diameter was selected using the standard criteria to be 0.63s cm (1/4 inch) . In the model it wns assumed that the nozzle would bo aligned parallel with CONDITION S-TrPE PITOT TUBE MIASUMJElfrS HADE AT THE 8-D SAJIPDING POUT FCK THE KIGH PU3U CMDITIOS equations (33) . (39), the average aspiration coefficients are A,(Rj,ej,iCj) . ,lys^ - . .IA„p,5, * ... * ,lAj,p55, {33) = -IAq^, * -lAjjpjj^ ♦ -‘''upjsA * ••• • -“dpssa (Si) [3S) s' ’ ■'‘'npsi * '**npi53 * •'''rpjst ' ••• * ol voloclti- at IVSaopIin* velocit)’ at i) . '‘ili* StoXes nuober based on the nozzle diatoecer, total velocity at 1 , and particle diaBeeer PPjjg. Dpjj- Midpoint particle diaaeters each ropreaentlnj IM of the Since the saaplloj velocity »ill deteraioe the volumo oocli traverse point, the total aspiration coefficient as aletermined by taXlng an average ueiphted according tdO) Khore = iniet velocity at traverse point j. Bocoose of the Hissing data at point I and negative pressure settlon point . 1 , these t« traverse points veto analysis. The totil aspirecion coefficients Table XXIX and XXX). There are two reasons for the relattye lo« amoim of concentration error found in this anaiyila. One reason is that the two nechnoisns causinj sopapUnj error, nocile i.isoli)!niBotit and aniso- kinetic aanpllng velocities, cause errors in the opposite direction. The S'type pitot tube detected a velocity less than or equal to the actual velocity which would load to oublsokinotte sanpllnj producinj an increased concentration. The notsle ■Isnligmnent when sanplini parallel to the stack wall would produce a decreased concentration. Sc values lead to sisall snapllni errors, even when isokinetic sanpllni conditions are not oaintainad. Mason erperlnentolly detnmined that the collection efficiency she prcainneely nidway between the hixh and low flow rate in this studv the flow pattema should be approxlwtely the same. The dlicreoancy between Mason's erpnrinental values and the values predicted by the simolatinn probably tan be accounted for as esperliaontal error by Mason. It would be nearly impossible to obtain a SOX sampling error for an aerosol as small ns the one used without eatramc anlsohinetic sampling conditions. Senplinit Velocity from S-Type Pitot Tubg f^secl Ntighted Average the naxltein 4)1- From Figure 15 It is apparent that by sptlttini the difference hetueen the angles where the velocity pressure drops off rapidly, it should be possible to gee within 20 degrees of the tero yaw nngle. This means that the sample velocity aeasored by the S-type pitot tube will be approxijiiBtely the same as the true total velocity In order to see how much greater the error would he for larger particles, a siellar analysis was perfomod using a dietributton with a 10 urn mass mean diameter and 2.3 geueetrlc standard deviation [see Figure 411. This was the distribution obtained at the outlet of .i eyelone In e liol-mia asphalt plant [43). Because of the larger dlametor particles tlie saapling efficiency ves reduced to 0.799 for the high flow five-hole pitot tube dnte an-celculoiad by multiplying the average e« velocity by the Inner duct area minus the core area. The flow rotes the average «ial velocity. The voluaetric floe •Jltiplying the average axial velocity by 7/8th o nation of the average velocity and the entire inn The results presented In Table 71tX. shoe that the insensitivity oi he S-typa pitot tube to yae angle produces a higher calculated flou le avernge velocity detontlnntion, this error Is reduced to 174. luid be expected Trorn looking > you angle {Figure IS). When the trovci ah appreximately 45 degrees, the S-type ose to the total velocity. Hovever, bej oc tube readings drop off quite rapidly ibe readings vere '0 degrees, the pito are presented It SimLkKY u bsttor undbrscandlnj; obtain a roprcsentativa sanpu of particulate omcter ftoa gas sttoaiia with coDploa flow pattrma. Tbe errors ioduced bv tangential flow were analyted relative to the flow streao velocity, and angle of the nottle relative to tl direction of flow. The second involved analysis of swirling flow patterns o tjielr eubsopuent effect on flow teeBsuroaents made by the S-type pitot tube. ■IsallgniaonT wore studied by taking conparativo anisokioetic and iaokinetic saoplea frm a straight section of duct. By anolyting the problan in this ■ethod the data obtained are more useful and have many sore applications beyond this study. They provide fundamental inforaation for a better under- ilonal profiles were oeesured at five asiel distances along the stack to Ths two aspects of this study, anisokinecic soapling BTTora and flow iDoasurooents, were coablned in a slnulation oodcl to dcceriBine the mainitude of errors whan an EP4 Method S eolssion test is perforoed at A sumary of tho laportoat results deteinined froo this study is as foUoMsi Tho flow patterns fc '0 degrees relative li such as swirling flow, is inherently self'presorving in round duets, it decays very slowly as it laoves up the stack and therefore sanplins any location downstreaa of the cyclone will Involve the sane problem. B. The yaw characteristics of the S-tj-pe pitot tube load to several equal to tho actual velocity with the nayiautn error being appronioately 5t. Beyond 45 degrees the aeasured velocity drops oft quite rapidly and at on angle of 70 degrees the aeasured volocitv is loss than half tho true velocity. Beesuse of its yaw characteristics, tho S-type pitot tube is not suitable for distinguishing the aslol oooponent of flow from the total flow which includes the taagential component. Voiumetrie flow calcuintlons bused on S-type pitot tube neasureeients in a swirling How tot tuoes boseo on cho fiye-ftole nnd throe-hole designs am s in detoTBining the velocity conponents iji a tangential The five-hcio pitot tube has the advantage of giving pitch 1 yen angle. Hovever, In a cyclonic tlo« iroaia, the yaw angio Is of wjch greater tnagnitude than the pilch angle Id therefore, the pitch angle can be Ignored with small error. In the .tuation modeled, if pitch angle were ignored Informetion ns D. The particle aampling errors due to nnlsoklnetlc sampling velocity and notzle aisaUinment were analyied and a eodel vas developed to describe the saapling efficiency as a function of velocity ratio (R} , misalignment angle fS) , particle diateeter, particle velocitv, and nozzle diameter. It was found that the maaiaum error far R » 1. approached (I - cosS], Mien both a nozzle nisalignBent and anisokinotic sampling velocltie.s are involved then the maslnim error epproachea |i - RcosSl. The aquations and their limiting conditions for predicting the aspiration coefficient are summarized in Table gXXIl. sties of particle aampling. However, when tho hlch is due to a reduced pro;ectcd notzle dine IS developed to ndjuBt cbe Stokes number to to IS analysed separately from tl Ik of tho total particulate at 9 has iDpUcationz Jut Borc laportaatlj' It Impilea that there nay he poasihu i>rohI»m 5 m obtainlpj auurste particle site data nsinj a device such as an •tapactoT. If the ccllectlon of particles in the pottle is particle ^iio dependent, then losses in the probe could lead to particle G. A similation nodel vas developed nhlch incorporates the inforsotion obtained in this study on particle soBpllng errors and the flou napping data. The particle sampling efficiency in a tangential flov stream ns, as eapectad, a function of partielo site. For a particle distribution with s mass scan diameter (IKD) of 3.0 pm and a geanetric standard deviation of 2.13, the sampling errors predicted more less chan 104. For a larger distribution with a mass mean diameter of 10.0 t* and geoiaetrie standard deviation of 2,3, a 304 sampling orrar uaa predictad. One of the reasons that the saitpllag errors were ss small os these ware, is that the two mechanisms inducing sampling bias produce errors In opposite directions. The missllgnitont of the nottle caused by the tangential velacicy component leads to a reduction of sample concentration. The reduced sampling velocity, calculated from 5-type pitot tube meesuremonts, leads to lublsolcinotlc sampling and an increased seaple ci if the ivernEe anjie of the flo» relntlve to the aiii of the otaet ij groacor then 10 ieirees, then EPA Method 5 should not be pstforaed. Sinoe the luslniua error io particle soaiplinj hes been found to bo (1 - RcosOi , the 10 degroe requirement Is undul>* restrictive end a 20 degree linitotlon .ould be more opproprioto. Per a 20 deiree angle, the velocity neasured by the S-typo pitot cube uould be epproaimetely the saiee ea the true velocity Cl.e., a . I). Therefore, ■e tl • CO ir moving to another location, because these suggestions, a better approach that it could bo used in a tangential either straightening the flow of the physioai limitations ol would be to laodify Method 5 si pitot tube, the direction of the flow could be accurately detorntinod for aligning the nottle, end the velocity components could bo measored threo-holc pitot tuba, the modification would hovo to inclndo a pro- tractor to measure the flow angle, an estra Tnommseter. andamothod of rotating the probe without rotating the entire impinger box. S5Sn;.:; ’ ■ ■' ■ tsrii a:.r WJ»«aR SK- ■ s a.K?".::.:~'£=S--a ■ src.’a**.'£r -ass.iTSi “ ■ :;:Si LpSKS." ss.a',s! :s“'x,s.”5s.-' “■ :“-t? srr» '•■ »y.»3:::;‘:.!: sr;=,‘fsar sa.'Si-C'aaa* "■ as= uaa\.arn;^sa=;.t;a.ag‘£j;:,'E;.. ■■- sa£.a£srs-,;:.£,‘ss,E“;,“ rs;:“ "- "■ ■- ■ ESI-Si.'; ‘ ■iiir“"”"' ■ ::;s:".,‘i,"‘;,.;:S-:L: ■ ES'iSE.,;; .5“’"- ■ “ =~- 1”^ sr;,::.’;src£3S“'“"- Florida, lelng a aenber of a Navy ftually, he was eonecantly on the Dova and actendod eight dll ‘ferent grade eohools and t-o high schools in Ha-aii, Virginia. Callfort lia and Eeotuchy. lie studied ceo years at Texas ASH IBivoreity and tli. ■n t-o at the Pennsylvania State University -here he received a g.S. in 1 Aerospace Engineering in 1971, his next three years -ere epoat -orhinf 1 -ich the Notional Acodcay of Scioneo and the Aaiericon FsjarholagUal AsBociacloa in Washinyton, D.C. In Sepceeber 1974 he began hU graduate education In Fnvlronieantal Engineering Scionces at the University of Flor ■ida. After receiving a Ibster of Engineering in August of 1975, he stayed on at the university as a graduate research assistant in pursu it of a Ph.D. for three years, the result ef vhleh is s=l|p~ Ibis dissertation sas subisittod to tha Gmduota Faculty of the College of En|lncerins and to die Graduate Council, end wes accepted as partial fulfillioent of the roc[ulre«ent5 for the degree of Doctor of Philosophy.